Method and apparatus for preventing evaporation from storage tanks



Aug. 24 1926. 1,597,399

R. E. WILSON METH OD AND APPARATUS FOR PREVENTING EVAPORATION FROM STD RAGE TANKS Filed y' 4 192s J7: nwizl)? 13/013622? Wag/2 J 1%. z/ Jazz" yz A Patented Aug. 24, 1926."

UNITED STATES. PATE'NT' OFFICE.

' ROBERT E. WILSON, OF CHICAGO, ILLINOIS, ASSIGNOR T STANDARD OIL COMPANY,

OF WHITING, INDIANA, AND CHICAGO,

ILLINOIS, A CORPORATION OF INDIANA.

METHOD AND APPARATUS FOR PREVENTING EVAPORATION FROM STORAGE TANKS.

Application filed May 4 The present invention relates to improvements in methods and apparatus for the prevention of the evaporation of stored liquids from storage tanks, and is intended more a particularly for use in connection with the storage of such liquids as gasoline, crude petroleum and the like. It willbe fully-understood from the following description, il-

lustrated by the accompanying drawing, in

which;

Fig. 1' is a plan view of a storage tank in connection with which the present invention is employed;

Fig. 2 is a vertical sectional view through 1 the tank illustrated in Fig. 1, and

Fig. 3 is a sectional detail view.

Referring more particularly to the drawings, the numeral 5 indicates a storage tank which may suitably have upright cylindrical walls 6. Within the tank 5 is provided a cover member 7, which may suitably be boat or dish-shaped so as to float upon the surface of the liquid stored within the tank. The cross-sectional dimensions of this floating cover member 7 are somewhat less than those of the interior of the tank, so that the latter is only partially closed by the floating cover 7 Suitable means may be provided to prevent the floating cover 7 from hugging the walls 6 of the tank at any point, for example, spring pressed roller plungers 8.

Drain pipes 7 may likewise be provided to drain through the cover any water that may collect on the surface.

It is readily apparent that in the construction thus described, the surface of the volatile liquid, for example, gasoline, in the tank is only partially covered and evaporation may take place from the uncovered or exposedportionthereof. In order to prevent loss of the vapors evolved from the exposed portion of the surface of the liquid, in accordance withthe present invention, I interpose between the exposed surface of the liquid and the atmosphere an expansible septum which is substantially impervious to the vapors evolved from the exposed surface of the liquid. This expansible septum, which is preferably formed of fabric impregnated with a suitable compound, pockets above the exposed surface of the stored liquid the vapors emanating therefrom and prevents their release and diffusion into the atmosphere. I

, 1923. Serial No. 636,589.

In general it is also desirable to protect the impervious septum thus described from external weather conditions. This may suitably be effected, for example, by employing in connection therewith a similar outer septum" or curtain of weatherproof material, for example a waterproofed fabric. If desired, a roof may be provided over the tank.

In the embodiment of the invention illustrated in the drawings, I have shown the protection of the exposed surface of the liquid or gasoline in the storage tank by means of a double curtain 9 extending entirely around the interior of the tank and secured at its upper end by any suitable means, such as the ring 10, to the exterior of the tank and secured at its inner end 11 around or near the periphery-of the floating cover, 7. The

The cylindrical curtain 9 completely incloses the exposed surface of the gasoline in the storage tank, forming a closed pocket Since the length of the 12 thereabove. double curtain 9 is sufficient to'permit the floating cover 7 to assume a position in the bottom of the tank, I find it advisable to provide means for supporting the slack in the curtain 9 existing when the cover 7 assumes a more elevated position. This may suitably be an annular, trough-like basket 13, secured to the floating cover 7 near its outer margin and extending part-1y into the pocket 12, and partly into the free space above the floating cover 7. Onrise of the floating cover 7, the folds of the curtain fall within this trough-like basket, as illustrated .in Fig. 2.

The double curtain 9, is formed as shown more in detail in Fig. 3. The inner ply or layer of the curtain is formed of a material substantially impervious to gasoline vapors, for example a fabric such as balloon silk thoroughly lmpregnated with gelatin'e, together with which may be incorporated .small proportions of a hardening agent such parts glycerine and one part water with to 1 %rof ferrous sulfate. This layer or ply of the curtain, designated by the numeral 14, forms a septum substantially impervious to the vapors arising from the ex-' posed surface of the gasoline and consequently confines or pockets the vapors in the space 12. The outer layer or ply 15 of the'curtain 9, that is, the portion exposed to the atmosphere, is substantially impervious 'to moisture and serves to protect the gasoline-proof septum 14 from exposure to rain or moisture which might injure it, and other atmospheric conditions. This ply or layer 15 may suitabl be formed of a fabric, such asv balloon sil impregnated with a suitable waterproofing agent, such as asphalt, paraflin, ceresin, rubber or the like. If desired, separate fabric need not be employed, but a single fabric may be coated on one side with the gelatinous composition and on the other with the waterproofing composition.

Although the present invention has been described in connection with the specific details of means for carrying it into effect, it is not intended that these details shall be regarded as limitations upon the scope of the invention, except in so far as included in the accompanying claims.

I claim:

1. The method of preventing evaporation of stored liquids such as gasoline andthe like, which consists in enclosing the space above the exposed surface of such liquids within a flexible septum impervious to such vapors, and interposing between said septum I and the" atmosphere means for preventing access of moisture to the former.

2. The method of preventing evaporation of stored liquids such as gasoline and the like, which consists in enclosing the space above the exposed surface of such liquids within a collapsible and expansible septum impervious to such vapors, and interposing between said septum and the atmosphere means for preventing access of moisture to the former.

3. In apparatusfor preventing'evapora tion of stored liquids such as gasoline, a storage tank at. least partially open to the atmosphere, and an expansible septum completely enclosing the-exposed surface of the gasoline, said septum comprising an inner gasoline-proof portion and an outer waterproof portion.

4. In apparatus for preventing evapora mg cover to assume a low position in said tion of stored liquids such as gasoline, a storage tank, a floating cover within said tank of smaller cross sectional area than the interior thereof, said cover being adapted to float on the surface of the contents of the tank, a curtain secured to the wall of the tank and extending therefrom to the floating cover, said curtain completely en- 'stantially impervious to water.

closing the uncovered portion of the contents of the tank and being substantially impervious to vapors arising from the liquid in the tank, the curtain permitting relative movement of the floating cover with respect to the wall of the tank.

5. In apparatus for preventing evaporation of stored liquids such as gasoline, a tank, a floating @ver within the tank of smaller cross-sectional area than the interior .thereof, said cover being adapted to float upon the liquid in the tank, and a flexible curtain extending from the floating cover to the wall of the tank and completely enclosing' the exposed portion of the'liquid in the tank, said cover comprising an inner portion impervious to the vapors arising from the liquid in the tank and an outer substantially waterproof portion. I

6. In apparatus for preventing the evaporation of stored liquids, a storage tank, a floating cover within said tank and of smaller cross sectional area than the interior thereof, said cover being adapted to float on the liquid in the tank, and a curtain secured around the upper margin of the tank on the one hand and approximately around the margin of the cover on the other hand, said curtain being substantially impervious to the vapors arising from the liquid in the tank and completely enclosing the exposed 'portion-thereo I 7 In apparatus for preventing the evaporation of stored liquids, a storage tank, a floating cover ,within said tank of less crosssectional area than the interior thereof, said cover being adapted to float on the liquid in the tank, and a curtain secured to the upper margin of the tank on the one hand and approximately to the outer periphery of the floating cover on the other hand, said curtain comprising an inner portion substantially "impervious to vapors arising from the liquid in the tank and an-outer portion sub- 8. In apparatus for preventing the evaporation of stored liquids, a storage tank, a

cover Within said tank of smaller cross-sectional area than the interior thereof, said cover being adapted to float on the surface of the liquid inthe tank, a curtain secured to the margin of the-tank on the one hand and to approximately the periphery of the I floating cover on the other hand, said ourtain being substantially impervious to vapprs arising from the liquid in the tank and.

ing of sufiicient length to permit 'the floattional area than the interior thereof,said

cover being adapted to float on the surface of the liquid in the tank, a curtain secured to the margin of the tank on the one hand and to approximately the periphery of the floating cover on the other hand, said eurtain being substantially impervious to vapors arising from the liquid in the tank and being of sufiicient length to permit the floating cover to assume a 10W position insaid tank, and trough-like means secured to the floating cover for supporting the curtain on rise of said cover.

ROBERT WILSON. 

